A novel control scheme for unbalanced power sharing and PCC voltage improvement based on the equivalent impedance in islanded microgrid

摘要

This paper introduces an equivalent negative sequence impedance control method and a negative sequence power-sharing scheme based on adopting virtual negative sequence resistance for the typical islanded microgrids with multiple distributed generation units and unbalanced loads. Firstly, the principle of the method that controls negative sequence components through negative sequence impedance control is discussed. Then a droop relationship between the controlled negative sequence impedance of distributed generations and their remaining power capacity is introduced, which achieves reasonable negative sequence current allocation among different distributed generation units. Moreover, to reduce the fluctuations of system frequency with unbalanced loads, a frequency feedback compensation loop is introduced. Finally, the simulation results verify the effectiveness of the proposed method.